<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        var num = 10;
        console.log(typeof num);//number
        var str = 'pink';
        console.log(typeof str);//string
        var flag = true;
        console.log(typeof flag);//boolean
        var vari = undefined;
        console.log(typeof vari);//undefined
        var timer = null;
        console.log(typeof timer);//object

        // prompt 取过来的值是 字符串型的
        var age = prompt('请输入你的年龄');
        console.log(age);//18
        console.log(typeof age);//string
    </script>
</head>

<body>

</body>

</html>